There are many typical uses for high intensity discharge (H.I.D.) lighting fixtures, such as for retail stores, warehouses, commercial buildings and other uses possessing relatively high ceilings. H.I.D. lighting fixtures have been highly successful due to their extreme amount of output of light. Sources of H.I.D. lighting are mercury vapor, metal halide and high pressure sodium.
These H.I.D. fixtures typically include a single light source lamp with a solid reflector utilized to direct the light in a downward direction. This reflector is normally a bell shape or conical shape. These prior art reflectors are made of reflective substances such as polished aluminum to enhance the efficiency of the fixture. The single lamp supplies direct light and light reflected off the reflector in a downward direction.
The great quantity of light supplied by these prior art H.I.D. fixtures, combined with atypical 1.5 to 1.7 light coverage criteria, wherein the light coverage is 1.5 to 1.7 times the open area of the fixture, allows for a greater light coverage area with fewer fixtures.
The drawbacks to using these prior art H.I.D. light sources are the use of excessive amounts of energy, poor color rendition, diminishing lumen output over the life of the lamp, no choice of color temperatures and a lack of high efficiency electronic ballasts to power the H.I.D. light sources.
An alternative prior art source of light has been fluorescent lamped fixtures. These fluorescent lamped fixtures have typically utilized long longitudinally extending cylindrical lamps, which are mounted at or slightly below the ceiling level, parallel to the floor surface. These prior art fluorescent lamp fixtures are usually one (1) to four (4) tubes of four foot to eight foot lengths per fixture, and these prior art fixtures utilize much lower wattage per fixture than the prior art H.I.D. light fixture. The fluorescent lamped fixtures illuminate a rectangular area and they are usually placed in rows mounted end to end. The draw back with the prior art fluorescent fixtures is the large quantity of lamp fixtures required and the lack of efficiency. The large quantities of prior art fluorescent fixtures significantly increases the initial installation costs, with no advantage or savings because of the increased labor cost, when compared to the installation of prior art H.I.D. light fixtures. The traditional fluorescent lamp also lacks the intensity needed for large spacing between lamps at high mounting levels.
New technology has brought about the compact fluorescent lamp, which is a four-prong lamp with two sets of joined ends creating a double inverted U effect relative to the base. The normal wattage for these double U-shaped fluorescent lamps is from 5 to 26 wattage per lamp. The biax fluorescent is another new technology utilizing a single elongated narrow "U" effect relative to the base. The normal wattage for these biax lamps is from twenty six (26) to fifty five (55) watts.
There have been several prior art patents utilizing these double U-shaped fluorescent lamps and socket combinations. Among the prior art patents are U.S. Pat. Nos. 4,520,436, 4,704,664 and 4,922,393, all of NcNair, U.S. Pat. No. 5,197,798 of Tickner and, additionally, U.S. Pat. Nos. 5,523,931 and 5,528,473 for high output fluorescent lighting fixtures, both of the Applicants Charles E. Kassay, J. Peter Kassay and Marc A. Kassay. McNair '436, McNair '664 and McNair '393 all describe light fixtures, which utilize only a pair of these small compact lamps, generally 3.4 inches to 7.6 inches in length. The double U-shaped lamps of McNair '436, McNair '664 and McNair '393 are mounted so as to be askew to each other in a reflector, which allows light out one end in quantities enough to replace small incandescent lamps (such as 50 W-100 W) in similar incandescent fixture configurations. The reflectors in McNair '436, McNair '664 and McNair '393 are also designed with openings in their respective upper sides to allow for the mounting of the socket, and connection of these sockets to the ballasts, which power the double U-shaped fluorescent lamps from outside the confines of the reflector. The complete light fixture packages of McNair '436, McNair '664 and McNair '393 are further encased in larger housings to enclose the wiring, ballasts, and sockets.
The usefulness of these fixtures of McNair '436, McNair '664 and McNair '393 over conventional incandescent fixtures is that the fixtures of McNair '436, McNair '664 and McNair '393 can replace higher wattage incandescent fixtures with a high percentage reduction of energy usage. Moreover, the lamp life of the double U-shaped fluorescent lamps utilized therein is longer than incandescent lamps of which the lamps of McNair '436, McNair '664 and McNair '393 can replace.
Another related prior art patent is that of Tickner, '798 wherein a light fixture utilizes a grouping of 26 watt compact fluorescent "Dulux D" double U-shaped lamps, with either six (6) lamps, eight (8) lamps, or twelve (12) lamps per fixture. Single or pairs of lamps are activated by individual ballasts. The lamps in Tickner '798 are mounted in a solid, non-translucent reflector so as to direct all light in a downward direction. The socket mounting plates in Tickner '798 are mounted within the concave reflector from 1/4 to 1/2 of the distance from the narrow base opening of the reflector to the wider light emitting output portion of the reflector. By combining this large number of 26 watt compact double U-shaped fluorescent lamps the fixture of Tickner '798 can produce as many as 14,400 initial lumens in an eight light configuration and 21,600 lumens in a twelve lamp configuration. These wattages produced by the device of Tickner '798 compare evenly with that of a 250 watt metal halide high intensity discharge lamp or a 200 watt high pressure sodium lamp. However, this low wattage compact fluorescent light fixture of Tickner '798 produces only approximately 69 lumens per watt, which is a significant drawback. The fixture of Tickner '798 at it's maximum potential cannot come near the very popular 400 watt metal halide H.I.D. high intensity discharge lamps for production of lumens, which initially produces 36,000 lumens, with a mean of 29,000 lumens.